So far, there is no single reactive dye which can produce a high black shade build up property. In order to get a high black shade build up property, a reactive dye composition which contains a plurality of reactive dye components has been used. Usually, one black reactive dye (for example, the following formula (I) black reactive dye) as the major component ##STR2## is mixed with red, orange, yellow or other shade reactive dye components to get the black reactive dye composition.
Black reactive dye compositions are already known from Japanese Patent Laid-open No. 58-160362, 63-178170, 1-315469, 2-73870, 2-202956, 8-104822, 8-253697, U.S. Pat. No. 5,445,654 and U.S. Pat. No. 5,611,821.
Due to strict requirements in energy saving and environmental regulations, advanced washing machines and highly efficient detergent have been continuously developed. The use of highly efficient detergent greatly improves the cleanness of washed materials. However, washed materials fade soon after several washings. This problem becomes worse if washed materials were dyed by the reactive black dye composition based on the major component of formula (I) black reactive dye. Therefore, there is a strong demand for a reactive black dye composition having good property in fastness of oxidative bleach and wash fastness.
A reactive black dye composition which is comprised of the above formula (I) black reactive dye as the major component and mixed with a plurality of reactive azo dyes fades soon after several wash. The reason is the poor property of the reactive black dye composition in fastness of oxidative bleach. Therefore, washed materials are caused to fade by the bleaching agent during washing.
If the additional dye components of the dye composition have different fastness of oxidative bleach, the washedmaterial may be caused to fade, and to change its hue as well. The currently commercially available black dye compositions commonly have this drawback. Because the formula (I) black reactive dye used in currently commercially available black dye compositions has poor property in fastness of oxidative bleach, the hue of the washed material will be caused to change after washing several times if the mixed red, orange, yellow, or other shade of reactive dye components have a better fastness of oxidative bleach, causing the washed block material to change to brown, or other hue.
In order to eliminate the aforesaid problem, there is a suggestion to select red, orange, yellow, or other shades of reactive dye components having the property of fastness of oxidative bleach approximately equal to the formula (I) black reactive dye. A black dye composition prepared according to this method may eliminate the change of hue, however it cannot prevent the washed material from being caused to fade by the bleaching agent.